During the manufacture of a semiconductor device several steps are commonly used with many types of devices such as microprocessors, memory devices, and logic devices. To adhere a semiconductor die to a paddle of a lead frame or to another support, an adhesive such as an organic resin or other flowable material is typically dispensed onto the paddle or other support and a semiconductor die is placed to contact the adhesive. A measured force is typically applied between the die and the lead frame to ensure adequate contact between the die and the adhesive, and a scrub may be used to facilitate adhesion between the die and the lead frame paddle. After curing the adhesive, terminals on the die are wire bonded to leads of the lead frame to electrically couple the die and the lead frame.
One problem encountered during semiconductor device assembly is referred to as "resin bleed." Resin bleed occurs when a portion of the adhesive which attaches the die to the lead frame flows from under the die to cover a portion of the paddle and may extend to cover a portion of the leads. This can result in poor or nonexistent electrical contact between the die and one or more leads to which the die is bonded, as the adhesive covers the bond site on the lead where the bond wire is attached. Resin bleed can also reduce adhesion between the lead frame and encapsulation material when the device is later encapsulated. Resin bleed is exacerbated when chemical components of the die attach adhesive separate with increasing temperatures thereby allowing the less viscous components of the material to flow more freely.
Various attempts have been made to reduce resin bleed, for example by increasing the cohesiveness and increasing the viscosity of die attach materials. Additional solutions for reducing resin bleed would be desirable.